434 proceedings: botanical society 



impregnating the wood. At first the growth was so rapid that the wood 

 cells were enclosed, as is the sand in "sand-calcites," but later it went 

 on more slowly, giving opportunity for the foreign matter to be ex- 

 cluded. The "phantom" line probably marks a temporary cessation 

 of growth. The absence of silica within the calcites, as well as other 

 relations, indicates that the deposition of silica was subsequent to 

 crystallization of the calcite. 



Discussion: D. F. Hewett mentioned the occurrence in certain 

 clays and residual soils of calcite grains surrounded by little quartz 

 grains, as though the quartz had been pushed aside by the growing 

 calcite. David White outlined different plausible explanations of the 

 structures described by Wherry. 



R. S. Bassler : The value of microscopic fossils in stratigraphy. The 

 speaker based his remarks upon the Early Tertiary Bryozoa of North 

 America, a monographic study of which has just been completed for 

 the U. S. Geological Survey. He showed with the aid of specimens 

 and lantern slides the methods of collecting, the preparation for study, 

 and the characters employed in the classification of these microscopic 

 fossils. Until recent years these fossil bryozoa have been considered 

 more as perforated stones than as well organized creatures in which the 

 perforation and ornamentation of their surface had definite physio- 

 logical purposes. The relation between the morphological and skeletal 

 variations and their physiological purposes was discussed, and finally 

 the stratigraphic results, particularly in intercontinental correlation, 

 were described. 



Discussion: E. O. Ulrich emphasized the fact that because these 

 fossils are studied microscopically, specific differences can readily be 

 established, and only specific characters are of definite time value. 



H. E. Merwin, Secretary. 



THE BOTANICAL SOCIETY OF WASHINGTON 



The 121st regular meeting of the Society was held in Assembly Hall 

 of the Cosmos Club at 8 p.m., Tuesday, May 1, 1917; 39 members 

 present. The meeting was called to order by the President. Mr. 

 Burt A. Rudolph and Mr. Horace W. Truesdell, Scientific As- 

 sistants in the Office of Fruit Disease Investigations, and Mr. Glenn 

 C. Hahn, Office of Forest Pathology, were elected to membership in 

 the Society. 



The regular program was devoted to a Symposium on the District 

 flora. Prof. A. S. Hitchcock gave an outline of the plan of the flora. 

 The flora of Washington has been studied for nearly 100 years. In 

 1831 Brereton's Prodromus of the Flora Columbiana, was published. 

 Ward's Flora, or Guide to the Flora of Washington and Vicinity, 

 was published in 1881 and several supplements have since been issued. 

 In 1906 a mimeograph list of the vascular plants of the District of 

 Columbia and vicinity was prepared by P. L. Ricker, Chairman of the 

 Botanical Seminar. The Seminar Committee on Spermatophyta con- 



